1. Field of the Invention
This invention relates to systems, apparatuses, methods, and computer program products relating to tracking and managing assets, such as medical assets, beverage containers, and manufacturing inventory. More particularly, the invention relates to using radio frequency identification (RFID) tags to track, manage, and maintain mobile and/or portable assets in a medical facility, shipping facility, inventory warehouse, or other similarly configured facility that houses mobile assets.
2. Discussion of the Background
In today's hospitals and medical environments asset management is very important, as hospitals make efforts to streamline operations to reduce overall operation costs. However, currently there are few tools available that allow hospitals to accurately track, maintain and properly distribute medical, and other mobile equipment (e.g., beds, wheelchairs, carts, laptop computers, etc.). Hospitals spend large amounts of funds on various medical supplies and apparatuses, but have few options available to track and manage their assets and ensure that their resources are being used as efficiently as possible.
Similar issues exist in other environments where the business relies on ready-use of mobile assets. For instance in a warehouse environment, various containers are often moved from one location to the next, with some uncertainty arising regarding a present location of a specific container at any given time. As more employees move containers from one location to another, or move groups of containers so as to access a specific container, the likelihood of a container being misplaced increases.
Applications of RFID technology are wide ranging and include detecting objects as they pass near to a sensor, uniquely identifying a specific tag and associated asset, and placing data relating to the tag into an RFID reader for later recovery. The process of reading and communicating with an RFID tag generally includes bringing the tag in proximity to an RFID sensor. Typically the RFID tags are active tags with an internal power source and emit a constant RF signal (or alternatively pulsed beacon). The RFID readers then detect the tag's emitted RF signal when the signal is within the range of the reader's emitted RF field (or receive range), and the readers receive and process the RF signal emitted by the tags. Thus, the reader detects the presence of an RFID tag by detecting its RF signal, and processes the received RF signal to accurately determine the unique identification code of the tag.
Alternatively, in other conventional systems, the RFID tags are passive until illuminated by the radio frequency field of the RFID sensor, at which point they become active. The RFID tag detects the presence of the field of the reader, and subsequently activates to send data, using various forms or protocols of hand shake occur between the tag and the reader, in order to exchange data. All of this communication between the tag's transponder and the sensor is performed using radio frequency energy of some kind. When multiple RFID tags are involved, anti-collision protocols are employed in order to multiplex or provide multiple accesses to the readers by the multiple tags. The main advantages of an RFID sensor and transponder system over the other forms of RFID tagging include (i) communication can occur within comparatively harsh operating environments; and (ii) the communication range between the sensor and transponder can be significant even when the RF frequencies are within the power limitations of the Federal Communications Commission (FCC) rules concerning unlicensed transmitters.
Accordingly, RFID technology is useful for several applications, especially those relating to security and asset management. For example, in an application where enhanced security is desired, RFID systems using electromagnetic energy with very low frequency are attractive since the very low frequency energy tends to suffer low losses from shielding materials such as metal boxes, aluminum foil, curtains, and the like. Those who would surreptitiously remove the tagged assets from a building usually try to use such shielding techniques. However, these low frequencies typically require large antennas with a transponder in order to achieve reasonable levels of RF coupling between the reader and the tag. It is impractical to place large wire antennas within small tags; accordingly, comparatively small magnetic loop antennas are the coupling methods of choice for such small tags. These magnetic loop antennas exhibit a serious drawback, however, in that they have characteristic “figure-8” sensitivity pattern and, in certain positions and/or orientations, can reject or otherwise not detect the fields generated from the sensor. Stated differently, magnetic loop antenna of the tag can only receive energy from the reader antenna coils only when the orientation of the reader and tag coils is similar. Specifically, the “rejection” solid angle for a loop antenna could be thought of as a band of a certain solid angle measured from the center and oriented 360° around the circumference of the loop. When such rejection occurs, the tag may be well within the sensor's intended field, but fails to detect the tag's emissions, and therefore also fails to communicate therewith. A related problem is when the position and/or orientation of the reader within the field is varied, thereby taking the readers out of the “figure-8” pattern of the tag antenna, and interrupting communication between the reader and tag.
Additionally, many existing RFID tag/reader systems do not have the ability to locate the tag in 3-dimensional space. As recognized by the present inventors, those that do have this ability suffer from significant drawbacks and some of them function using the low frequency signals needed to pass through foil and other shielding. The added capability of the spatial positioning, however, allows the reader to gather more information about the tag, i.e., its relative spatial location with respect to the sensor or some other reference point. This capability provides a very significant advantage over other asset management systems (RFID or otherwise) which cannot determine the position of the assets.
Other prior art asset tracking systems have been implemented using RFID tag readers with consistent, similar antenna pattern designs. This design, however, requires the use of triangulation techniques in an attempt to pinpoint the exact location of a specific asset or RFID tag. These systems fail to have the precision needed to detect that an RFID tag is on a specific floor, or that the tag is located in a specific room if readers are located in two adjacent rooms. In a system with poor tracking fidelity, tracking the assets using software proves to be difficult because the exact location of the tag can not be determined to the precision required by the tacking software.
Conventional systems have also implemented infrared IR detection systems to perform asset tracking functions, however the present inventors recognized a drawback to implementing such a system is that the reader and the IR tag must be in visual range of one another for the tag to be properly read. Thus, assets can be easily moved without being detected by the IR tag reader, making accurate asset tracking difficult.
Additionally, the conventional systems described above include RFID tags of various elongated shapes, which are not always compatible with the various assets that are to be tracked. Specifically, difficulties are encountered with large RFID tags are to be attached to small devices and therefore make using the small device awkward and cumbersome. Also, as discussed above, the various tag designs cause the RF field emitted from the tag to be non-uniform and thus dependent upon the orientation of the tag for detection.
Furthermore, such conventional systems fail to be supported by sufficient software systems that manage, track and allow maintenance of the assets including the RFID tags. The conventional systems allow the assets to be tracked; however they do not provide specialized functionality for the hospital environment.